From the beginning of time we've searched for a way to stop the clock and stay young. Can science show us the way? The key could be in our blood.

What's the secret to youth? Some say it's in your genes, but Harvard Stem Cell Researcher Amy Wagers, PhD, says it may be in the blood.

"There's this sort of long term communication that's happening through a number of different substances that are traveling in the blood and are sort of telling different parts of the body how old you are," Wagers told ABC30.

Her team's research builds on a decade of studies showing young blood has anti-aging effects on older mice, utilizing a technique dating back 150 years.

"It's called parabiosis and it involves basically conjoining the circulatory systems of two animals kind of like you would imagine Siamese twins," Wagers explained.

Research shows the young blood rejuvenates the heart muscle and brain activity of older mice.

Wagers said, "It appears not just to be a slowing of the accumulation of changes that occur with age, but an actual reversal of those changes."

Now Wagers' team believes a protein in the blood could be responsible for the effects known as growth differentiation factor eleven or GDF-11.

"We can add back this protein into animals that have already aged and restore function to them," Wagers said.

Wagers is hoping to study the GDF-11 protein in human trials within the next three years, and she's not the only one. Another research team from Stanford just began a study giving a transfusion of blood plasma donated by young people to patients with moderate to mild Alzheimer's, paving the way for new therapies, perhaps for diseases like Alzheimer's and ALS.